MY EXPERIENCE IN INDUCING EARLY FLOWERING OF DURIAN
SCIENTIFIC NAME: Durio zibethinus
FAMILY: Bombacaceae
Durian is a high return crop. Those which could produce early crops could receive an unusually high price for their fruits. Early fruiting does not mean only to fetch the high price but it extends the fruit season as well.
I have established the 120-acre orchard since 1953. It comprises of gentle slope land with deep well-drained sandy loam soil.
There are durian and rambutan in this same number, viz 1,500 trees each. Water supply is enough to irrigate the orchard all year round.
The leading variety of durian planted in the orchard is Chanee. The plants are 20 years old and planted at 10 x 10 meters. This spacing allows good sunlight and good ventilation around the orchard, therefore the diseases are minimized.
FACTORS AFFECTING EARLY FLOWERING
It has long been believed that weather condition is a main factor that causes flower bud initiation. In the past 2-3 years even the soil in the durian orchard was wet due to sporadic rain during October-November. The flower bud initiation occurred earlier than usual. This phenomenon seems to indicate that weather condition (dry-wet condition) is not the main factor for flowering in durian.
I do not believe that early flowering could be induced by planting selected early flowering clone since all the varieties in my orchard produced early flowering when they were treated correctly. Now I do believe that the most important factors in inducing early flowering are proper care and proper application of flower regulators.
HOW TO INDUCE EARLY FLOWERING
1. Use the right fertilizer grade
In the past 4-5 years, I regularly applied fertilizer of 15-15-15 grade to my orchard. In recent years the fertilizer grade has been shifted to 8-24-24 either at the rate of 2.5 kgs/tree of 10-year-old or 4.5 kgs/tree of 20-years-old. The application was made once a year. I believe that low-nitrogen grade fertilizer could cause early flowering.
It was noticed that after applying low-nitrogen fertilizer grade, the trees became rigid and strong and the incidence of Phytophthora disease was less.
2. Foliar fertilizer application
The durian orchard was divided into two plots. Each plot was treated differently. On the first plot, the foliar sprays with Sea Plus F at 20 cc in 20 litres of water were applied following the soil application stated in (1). The foliar spray was made at 15-20 day intervals until the flower buds were visible. The spray was resumed when fruit set was evident and repeated until fruits were nearly mature. Such practices seem to induce early flowering of the following year.
The second plot was treated with various chemical compounds:
[a] 'This' at 40 cc in 20 litres of water;
[b] Foliar fertilizer grade 10-52-17 at 400 grams in 200 litres of water;
[c] Potassium nitrate grade 14-0-46 at 600 grams in 200 litres of water.
These three compounds were thoroughly sprayed on the trees. The first spray was done in conjunction with the soil application. The following sprays were done at 15-20 day intervals until the flower buds were visible. The spray was resumed when the fruits reached the betel nut size and repeated until fruits were nearly mature. This practice gave similar result as the aforesaid practice. It is suggested that 'This' spray should be omitted at flushing stage and resume spraying when the leaves are nearly mature.
In the dry season, the orchard was irrigated at 5-day intervals. The amount of water applied depends on soil moisture-holding capacity of each particular soil type. Branch pruning to permit more light exposure and better air movement helps the trees to flower better.
I personally believe that inducing early flowering of healthy durian trees could be made successfully.
NOTE: The above article on Durian was obtained by John Marshall during the 1985 S.E. Asia Fruit Tour to Bangkok.
DATE: March 1987
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